Film assemblage for color diffusion transfer

ABSTRACT

A photographic film pack or magazine containing all of the materials and components required to produce a plurality of diffusion transfer process color reflection prints. The pack includes a plurality of diffusion transfer process color film units each comprising a photosenstive laminate including as essential layers, in order, a dimensionally stable transparent support layer, a layer adapted to receive a diffusion transfer process dye image-forming material diffusible thereto, an opaque layer, a photosensitive silver halide layer having an associated diffusion transfer process dye image-forming material; a transparent dimensionally stable support sheet superposed substantially coextensive with the surface of the laminate opposite the transparent support; and a rupturable container, filled with a liquid processing composition including an opacifying agent, secured to the exterior of the laminate and transparent sheet adjacent a leading edge of either or both the external transparent layer and sheet in position to discharge its liquid contents between the transparent sheet and the laminate by and in response to the application of compressive pressure to the container. The film pack also comprises a container including a forward wall formed with a light transmitting opening and holding a plurality of film units arranged in stacked relation with the transparent sheets facing the forward wall in position for exposure to light admitted by the opening, and an opening at one end through which exposed film units can be withdrawn, one at a time, to effect the processing thereof. The container also includes pressure-applying means associated with the withdrawal opening for discharging and spreading the liquid contents of the container of each exposed film unit as the latter is withdrawn from the film pack container. A dark slide with a leader projecting beyond the pressure-applying means is positioned between the exposure opening and the foremost film unit to prevent exposure thereof and is connected by a leader to the foremost film unit which, in turn, is connected to the next succeeding film unit, and so forth, to provide for withdrawal and processing of all film units.

United States Patent 1191 Rogers [111 3,765,887 [451 Oct. 16, 1973 FILM ASSEMBLAGE FOR COLOR DIFFUSION TRANSFER [75] Inventor: Howard G. Rogers, Weston, Mass.

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: Apr. 24, 1972 [21] Appl. No.: 246,563

Related- US. Application Data [63] Continuation-in-part of Ser. No. 203,731, Dec. 1, 1971, which is a continuation of Ser. No. 159,254, July 2, 1971, Pat. No. 3,689,262, which is a continuation-in-part of Ser. No. 39,646, May 22, 1970, Pat. No. 3,594,165, which is a continuation-in-part of Ser. No. 815,585, April 14, 1969, abandoned, which is a continuation-in-part of Ser. No. 728,535, May 13, 1968, abandoned,

3,680,456 8/1972 Nerwin 96/76 R Primary Examiner-Norman G. Torchin Assistant Examiner-R. L. Schilling Attorney-Robert E. Corb et al.

[57] ABSTRACT A photographic film pack or magazine containing all of the materials and components required to produce a plurality of diffusion transfer process color reflection prints. The pack includes a plurality of diffusion transfer process color film units each comprising a photosenstive laminate including as essential layers, in order, a dimensionally stable transparent support layer, a layer adapted to receive a diffusion transfer process dye image-forming material diffusible thereto, an opaque layer, a photosensitive silver halide layer having an associated diffusion transfer process dye imageforrning material; a transparent dimensionally stable support sheet superposed substantially coextensive with the surface of the laminate opposite the transparent support; and a rupturable container, filled with a liquid processing composition including an opacifying agent, secured to the exterior of the laminate and transparent sheet adjacent a leading edge of either or both the external transparent layer and sheet in position to discharge its liquid contents between the transparent sheet and the laminate by and in response to the application of compressive pressure to the container.

The film pack also comprises a container including a forward wall formed with a light transmitting opening and holding a plurality of film units arranged in stacked relation with the transparent sheets facing the forward wall in position for exposure to light admitted by the opening, and an opening at one end through which exposed film units can be withdrawn, one at a time, to effect the processing thereof. The container also includes pressure-applying means associated with the withdrawal opening for discharging and spreading the liquid contents of the container of each exposed film unit as the latter is withdrawn from the film pack container. A dark slide with a leader projecting beyond the pressure-applying means is positioned between the exposure opening and the foremost film unit to prevent exposure thereof and is connected by a leader to the foremost film unit which, in turn, is connected to the next succeeding film unit, and so forth, to provide for withdrawal and processing of all film units.

20 Claims, 9 Drawing Figures PATENIEDBU 15 1915 3.765887 SHEET 2 0F 5 52 EwmEwEE 5:3 QZNQESNZ/ PATENTEUnm 16 ms 3.765887 SHEET 5 OF 5 52 FIG.9

FILM ASSEMBLAGE FOR COLOR DIFFUSION TRANSFER RELATED APPLICATIONS This application is in part a continuation of copending U. S. Patent application Ser. No. 203,731, filed Dec. 1, 1971, which is a continuation of application Ser. No. 159,254, filed July 2, 1971, now U.S. Pat. No. 3,689,262, which is in part a continuation of application Ser. No. 39,646, filed May 22, 1970, now U. S. Pat. No. 3,594,165, which is in part a continuation of Ser. No. 815,585, filed Apr. 14, 1969, now abandoned, and which in turn is in part a continuation of application Ser. No. 728,535, filed May 13, 1968, now abandoned.

BACKGROUND OF THE INVENTION The present invention is concerned with photographic diffusion transfer process film packs adapted for use in so-called self-developing cameras.

Film packs or magazine designs of the type adapted to be employed in combination with film pack cameras and such cameras are disclosed in a multiplicity of U. S. Patents including, but not limited to U. S. Pat. Nos. 3,426,664; 3,443,500; 3,460,452; 3,543,662; 3,550,515; 3,561,339; 3,587,426; 3,593,631; 3,595,661; 3,607,279; 3,607,283; and 3,615,436.

In commercially available diffusion transfer process film units and film packs, each film unit typically comprises a photosensitive sheet and a second sheet which are normally separated or designed to be separated from one another during exposure; and following exposure, the photosensitive sheet is moved into superposition with the second sheet and the two are advanced between a pair of pressure-applying members for distributing a liquid processing composition therebetween. The photosensitive element may contain an integral print-receiving stratum or the second sheet-like element may comprise a transfer image-receiving element. Subsequent to transfer processing, the imagecarrying area of the image-receiving element is generally separated from the laminate.

An improvement over this type of the film unit or assemblage is to be found in an integral film unit in-which the photosensitive and second sheet-like elements are retained in superposed relation prior to, during, and subsequent to processing. Film units and film packs of this latter type are disclosed in the aforementioned U.S. Patents as well as U.S. Pat. Nos. 3,415,644, 3,473,925,

3,619,192, 3,619,193, and 3,621,768.

In such film units, one of the elements which may function, in effect, as the image-receiving element because the layer of image-receiving material is located between it and the photosensitive laminate, is transparent to permit both exposure of the photosensitive material and viewing of the transfer image. Exposure of such a film unit by the usual camera system would result in an image appearing to be geometrically reversed, i.e., a mirror image, so that the camera must be specially designed with an image reversal system including means such as a mirror in order to produce a geometrically correct-appearing transfer image.

Photographic film units in which the layers thereof are retained in superposition prior to, during, and subsequent to processing and which can be exposed with a conventional camera optical system and which can be processed to produce an image which is not geometri cally reversed as is a mirror image, are disclosed, for example, in U.S. Pat. Nos. 3,594,164 and 3,594,165.

In general, color photographic reproduction may be provided by diffusion transfer processing such as exposing a photoresponsive material, for example, a photosensitive silver halide layer having associated therewith dye image-providing material which is processing composition diffusible, as a function of exposure of its associated photosensitive silver halide, such as the dye image-providing materials disclosed in U. S. Pat. Nos.

3,087,817; etc., as adapted to provide imagewise differential transfer of dye image-providing material to a contiguous image-receptive element providing dye image formation to such element as a function of the point-to-point degree of silver halide layer photoexposure.

The prior art also suggests a number of so-called selfdeveloping film unit structures and/or assemblages of film units in the form of packs and the like, incorporating means for rupturing a container of processing liquid, ejecting the liquid contents of the container between a pair of superposed photographic sheets and/or spreading a liquid processing composition between a pair of sheets as the latter are moved into superposed relation. In most, if not all, cases the two sheets are separated prior to and subsequent to exposure so that the structures involved also include means for manipulating or holding the sheets separately or apart from one another prior to and during exposure and/or guiding the sheets into superposition subsequent to exposure. In most instances, the liquid spreading means are inexpensive and expendable along with the other components remaining after prints have been made. Typical structures of thistype are described in a multiplicity of U.S.Patents including, but not limited to U.S. Pat. Nos.

2,930,301, 3,037,670, 3,047,387, and 3,101,656.

SUMMARY 'OF THE INVENTION Objects of the invention are: to provide a photographic, self-developing film pack of the type described useful with conventional photographic camera exposure systems to produce a plurality of diffusion transfer process color reflection prints and incorporating processing means for distributing a processing liquid within each film unit to effect print formation during withdrawal of the film unit from the pack, thus eliminating the need for providing separate processing means within the camera; and to provide a photographic film pack assembly of the type described adapted to function in the nature of a self-developing camera back which can be employed with a conventional camera exposure system.

These and other objects of the invention are achieved in a simple and relatively inexpensive and hence expendable film pack assemblage which not only incorporates the film units including the materials required to produce a plurality of diffusion transfer process color reflection prints, but the means for effecting the processing of the film units to produce such prints. These last-mentioned means include a simple and inexpensive structure which is a part of the container, for applying compressive pressure to each film unit as it is wighdrawn following exposure from the container in which it is supplied and exposed. The film pack assembly of the invention may be loaded into or coupled to the rear of almost any conventional camera body having the optical capability of producing an image of the appropriate size and the requisite and relatively simple structure for holding the film pack in proper position, thereby converting the camera to a self-developing camera capable of producing diffusion transfer process color reflection prints.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the product possessing the features, properties and the relation of components which are exemplified in the following detailed disclosure, and the scope of the application of .which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings.

FIG. 1 is a fragmentary perspective view of one embodiment of a photographic film unit in accordance with the invention;

FIGS. 2, 4, and 6 are diagrammatic, enlarged crosssectional views of the film unit of FIG. 1, taken substantially along the line 22, illustrating the association of elements during the three illustrated stages of the performance of a diffusion transfer process, for the production of a multicolor transfer image according to the invention, the thickness and relative proportions of the various materials and components being exaggerated or distorted for purposes of clarity of illustration, and wherein FIG. 2 represents an exposure stage, FIG. 4 represents a processing stage and FIG. 6 represents a product of the process; and

FIGS. 3,5 and 7 are diagrammatic, enlarged sectional views of the film unit of FIGS. 2, 4, and 6, substantially along the lines 3-3, -5, and 77, respectively, further illustrating, in detail, the arrangement of layers comprising the photosensitive laminate during the three illustrated stages of the transfer process.

FIG. 8 is a partially exploded perspective view of a film pack comprising an assemblage of film units and constructed in accordance with the invention; and

FIG. 9 is a longitudinal sectional view taken substantially midway between the sides of the film pack of FIG.

DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, the preferred form of the film assemblage for the production of a dye reflection print comprises a photosensitive film unit specifically adapted to be processed in the presence of ambient radiation and the dye reflection print image to be viewed during and subsequent to processing without separation of film unit components including a first photosensitive sheet element comprising a transparent support carrying on one surface a diffusion transfer process dye image receptive layer, an opaque layer and at least one layer of a photoresponsive material having associated therewith a dye image-providing material, which is processing composition diffusible as a function of the photoexposure of its associated photoresponsive material to produce photographic information recordation. The film unit additionally includes a second transparent sheet element superposed coextensive the surface of the first sheet opposite its transparent support; a rupturable container containing a fluid agent including an opacifying agent for distribution between the first and second sheet elements for reacting with exposed photoresponsive material for forming the image in the image-receptive layer; means including a leader for coupling film units and selectively withdrawing the units sequentially from a film pack or magazine; and the opacifying agent disposed in the processing composition, taken together with the opaque layer, adapted to prevent exposure of the first sheet elements photoresponsive material by radiation actinic thereto incident on the film unit in the processing mode.

The preferred form of film pack or magazine embodying the designated film units comprises a plurality of the film assemblies, each adapted. to be individually exposed in a camera, enclosed in a light-proof container which allows the film units to be sequentially exposed. The container includes a forward wall having a light-transmitting section, e.g., an exposure aperture, therein and an opening in one end through which film assemblies can be individually withdrawn. The photosensitive film units are positioned together in stacked relationship within the container underlying the exposure aperture with the exposure surface of each film unit foremost and the rupturable container positioned adjacent the opening through which the film units are withdrawn so that following the exposure of each film unit, the unit is moved, by drawing on the leader of the film unit, and withdrawn from the container through the opening. The film pack is initially provided with a cover element or sheet mounted within the container and extending across the exposure aperture for closing the aperture against the admission of light. The cover element also includes a leader extending from the container through the opening and being removable therethrough.

The film pack is employed by bieng positioned in and coupled to the rear of a camera body of a conventional or slightly modified type adapted for use with film magazines or packs and including means for locating the pack so that the forwardmost film unit is substantially at the exposure plane of the camera. A leader of the cover element extend from the pack and from the camera where the last-mentioned leader may be grasped for withdrawing the cover element from the pack between the pressure-applying members to allow the film units of the pack to be selectively exposed. After each successive film unit is exposed, that film unit is then individually withdrawn from the container and camera between the pressure-applying members by withdrawing the leader of the first film unit and of each successive film unit from the container and camera.

By employing the film assemblages of the present invention, color reflection prints can be provided employing photographic diffusion transfer processing effected external the camera in which the film units were subjected to exposure and in the presence of ambient radiation.

Multicolor images may be obtained using color imageforming components in the diffusion transfer process of the present invention by several techniques. One such technique contemplates employment of an integral multilayer photosensitive element containing at least two selectively sensitized photosensitive strata, each having associated therewith a dye imageproviding material exhibiting desired spectral absorption characteristics. As is disclosed, for example, in the aforementioned U. S. Pat. No. 2,983,606 employing dye developers (dyes which are also silver halide developing agents) as the dye image-providing material, a suitable photosensitive element of this type includes a red-sensitive silver halide stratum, a green-sensitive silver halide stratum and a blue-sensitive silver halide stratum, said strata having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be utilized in the silver halide stratum, for example, in the form of particles, or it may be employed as a layer behind the appropriate silver halide strata. Each set of silver halide strata and associated dye developer strata are disclosed to be optionally separated from other sets by suitable interlayers, for example, by a layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted. For purposes of simplicity and clarity, in the following detailed description of an illustrative film unit contemplated by this invention, reference will be made to dye developers as the dye image-providing materials. It will be appreciated, however, that the invention is not restricted to any particular imaging system and other imaging systems, e.g., the imageproviding materials disclosed in any of the aforementioned patents, may be employed instead.

In a preferred embodiment of the present invention, the film unit is specifically adapted to provide for the production of a multicolor dye transfer image and the photosensitive laminate comprises, in order, at least two selectively sensitized silver halide emulsion strata each having dye image-providing material of predetermined image color subsequent to processing associated therewith which is soluble and diffusible, in alkali, at a first pH, as a function of the photoexposure of its associated silver halide emulsion stratum; an alkaline solution permeable opaque layer; an alkaline solution permeable polymeric layer dyeable by the dye imageproviding materials; an alkaline solutuion permeable polymeric layer containing sufficient acidifying capacity to effect reduction, subsequent to substantial multicolor transfer dye image formation, of a processing composition having the firstpl-l to a second pH, at which the dye image-providing material is substantially non-diffusible; and the dimensionally stable transparent layer.

The silver halide emulsions comprising the multicolor photosensitive laminate preferably possess predominant spectral sensitivity to separate regions of the spectrum and each has associated therewith a dye image-providing material, possessing subsequent to photoexposure or processing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion. Specifically preferred dyes comprise dyes which exhibit major spectral absorption outside of the primary regions of the spectrum to which the associated silver halide emulsion is sensitive and a spectral transmission substantially complementary to that absorption, during exposure of the emulsion, and major spedtral absorption within the spectral range to which the associated silver halide emulsion is sensitive and spectral transmission substantially complementary to said absorption, subsequent to exposure or processing of said emulsion, for example, of the type disclosed in U. S. Pat. No. 3,307,947.

In one embodiment each of the emulsion strata, and its associated dye, may be spaced from the remaining emulsion strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers and the dyeable polymeric layer next adjacent the polymeric acid layer may be separated from that layer by an alkaline solution permeable polymeric spacer layer,

most preferably a polymeric spacer layer having decreasing permeability to alkaline solution with increasing temperature.

In such embodiments of the invention, the silver halide emulsion comprises photosensitive silver halide dispersed in gelatin and is about 0.6 to 6 microns in thickness; the dye itself may be dispersed in an aqueous alkaline solution permeable polymeric binder, preferably genatin, as a separate layer about 1 to 7 microns in thickness; the alkaline solution permeable polymeric interlayers, preferably gelatin, are about 1 to 5 microns in thickness; the alkaline solution permeable and dyeable polymeric layer is transparent and about 0.25 to 0.4 mil. in thickness; the alkaline solution polymeric spacer layer is transparent and about 0.1 to 0.7 mil. in thickness; the alkaline solution permeable polymeric acid layer is transparent and about 0.3 to 1.5 mils. in thickness; and the dimensionally stable transparent layer is alkaline solution impermeable and about 2 to 6 mils. in thickness. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

Employment of the detailed film unit of the present invention, according to the hereinafter describedcolor diffusion transfer photographic process, is specifically adapted to provide for the production of a color transfer image accomplished by a diffusion transfer process which may include in-process adjustment of the environmental pH of the film unit, from a pH atwhich transfer processing is operative to a pH at which dye transfer is substantially inoperative, subsequent to substantial transfer image formation, in order to obviate the previously discussed disadvantages of the prior art products and processes. The color transfer image is thus obtained and maintained irrespective of the fact that the film unit comprises an integral laminate unit during exposure, processing and subsequent viewing, and storage of the unit. Accordingly, by means of the present invention, color transfer images and specifi-t cally multicolor images may be obtained, employing an integral laminate film unit, which exhibit desired maximum and minimum dye densities; yellow, magenta and cyan dye saturation; red, green and blue hues; and color separation, over an extended period of time, as compared with prior art disclosed film materials. These unexpected advantages are in addition to the manufacturing advantages obtained by reason of the present inventions integral color transfer film unit and which will be readily apparent from examimantion of the units parameters, that is, for example, advantages in more efficient utilization of fabricating materials and components, enhanced simplicity of film manufacture and camera design and construction, and more simplified and effectively controlled customer utilization of the unit.

Reference is now made to FIGS. 1 through 7 of the drawings wherein there is illustrated a typical photographic film unit embodying the present invention and wherein like numbers appearing in the different figures refer to like components.

As previously noted, FIG. 1 shows in perspective, a film unit designated 10, and each of FIGS. 2 through 7 illustrate diagrammatic cross-sectional views of film unit 10, taken along specified section lines to show the film unit during the various stages in the performance of a photographic diffusion transfer process as detailed hereinafter.

Film unit 10 comprises rupturable container 11 containing, prior to processing, aqueous alkaline solution 12, photosensitive laminate 13 including, in order, blue-sensitive silver halide emulsion layer 15 containing yellow dye developer; interlayer 16; green-sensitive silver halide emulsion layer 17 containing magenta dye developer; interlayer 18; red-sensitive silver halide emulsion layer 19 containing cyan cye developer; opaque layer 20; image-receiving layer 21; spacer layer 22; neutralizing layer 23; and dimensionally stable transparent layer 24. A dimensionally stable transparent sheet is provided adjacent emulsion layer 15 and both layer 24 and sheet 25 preferably comprise an actinic radiation transparent and processing composition impermeable flexible sheet material.

The assemblage or film unit is provided with a sheetlike binding element 26 extending around the lateral and trailing end edges of the assemblage for maintaining the laminate l3 and sheet 25 comprising the assemblage intact except at the interface between the laminate and sheet 25 during distribution of processing composition 12 therebetween. As illustrated in the drawings, binding element 26 may take the form of a strip or tape secured around and to the margins of sheet 25 and element 24 securing the sheet and laminate together at the lateral and one(trailing) end edges. Tape 26 will also act to maintain processing composition 12 intermediate sheet 25 and photosensitive laminate 13 upon application of compressive pressure to container 11 and distribution of its contents intermediate the stated elements. Under such circumstances, binding tape 26 will act to prevent leakage of processing composition from the film unit during and subsequent to photographic processing. In the preferred embodiment illustrated, that portion of binding sheet 26 which overlies the lateral edge section of transparent sheet 25 is narrower than the portion of binding tape 26 overlying transparent support layer 24 in order to insure processing distribution and resultant dye image foramtion in an area extending to the edges of the viewing area defined on three sides by the portion of the binding tape overlying transparent sheet 2 4 through which the dye image is to be viewed.

In addition, as illustrated, binding sheet 26 overlying and secured to the trailing edge sections of transparent sheet 25 and transparent support layer 24 cooperates with the trailing edge of the sheet and support layer to provide an enclosed chamber or trap space 60 adapted to collect and retain excess processing composition 12 overrun. Excess liquid is initially provided in container 11 to insure adequate processing composition coverage upon distribution and the trapping space collects the overrun beyond the trailing edge sections of the transparent sheet and support layer to prevent escape of the processing liquid. To further facilitate distribution of processing composition 12 between transparent sheet 25 and photosensitive laminate l3, binding member 26 may be provided with one or more air release vents (not shown) associated with the trailing edge section of the film unit and in direct communication with trapping chamber 60 in order to facilitate release of air from the film unit during distribution of processing composition 12.

Rupturable container 11 may be of the type shown and described in any of US. Pat. Nos. 2,543,181; 2,634,886; 7 2,653,732; 2,723,051; 3,056,491; 3,056,492; 3,152,515; and the like. In generah such containers will comprise a rectangular blank of fluidandair-impervioussheet material folded longitudinally upon itself to form two walls 27 which are sealed to one another their longitudinal and end margins to form a cavity in which processing solution 12 is retained. The longitudinal marginal seal 28 is made weaker than the end seals so as to become unsealed in response to the hydraulic pressure generated within the fluid contents 12 of the container by the application of compressive pressure to wall 27 of the container.

As illustrated in FIGS. 1, 2, and 4, container 11 is secured toand extends transverse a leading edge of photosensitive laminate 13 in position to effect unidirectionaldischarge of the containers contents 12 intermediate thefacing surfaces of transparent sheet 25 and blue-sensitive silver halide emulsion layer 15 by and in response to the application of compressive pressure to walls 27 of container 11. Thus, container 11, as illustrated in FIG. 2, extends transverse a leading edge of laminate 13 with its longitudinal'marginal seal 28 directed toward the leading edge of laminate l3 and sheet 25. Container 11 is secured to laminate 13 by an extended portion 30 of binding sheet 26 extending'over a portion of one wall 27 of the container, in combine tion with a separate means such as a sheet or strip des ignated 31 extending overaml secured to at least a pmtion of the other wall 27 of the container and a portion of the outer surface of sheet 25 overlying an area of laminate 13 generally coextensive with the area covered by retaining sheet 26(Sheet 31 is shown to have a leading end section designated 38 and a trailing end section 40 at which sheet 31 is coupled with the film unit near the leading endthereof. As will be detailed hereinafter, sheet 31 also serves as a leader sheet to facilitate withdrawal of the film unit.

W Transparent sheet 25 is coextensive with and maintained in superposed, face-to-face relation with the blue-sensitive emulsion layer 15, at least during processing, to facilitate distribution of processing composition 12 by and in response to movement of the film unit between a pair of pressure-applying members.

As illustrated in FIG. 6, the extended portion 30 of binding sheet 26 may be of such area and dimensions that, for example, upon manual separation of containerl and sheet 31 from the remainder of film unit 10 subsequent to distribution of the composition, portion 30 may be folded over the edge of laminate l3, previously covered by sheet 31. This is important to facilitate maintenance of the laminates structural integrity during the flexations inevitable in storage and use of the processed film unit. Preferably, however, the film unit will be maintained intact subsequent to processing including retention of the emptied container, the processing composition and transparent sheet in the spacial position assumed during processing. In such instance, the processing composition employed should possess the requisite adhesive capacity, in both the fluid and dry states, to enhance the integrity and stability of the spacial structure thus formed.

In a particularly preferred embodiment of the film unit, the opacity of processing composition 12, when distributed will usually be sufficient to prevent further exposure of the film units silver halide emulsion or emulsions by actinic radiation transmitted by transparent sheet 25 during processing of the unit in the presence of radiation actinic to the emulsion oremulsions. Accordingly, the film unit may be processed, subsequent toe xposure, in the presence of such radiation in view of the fact that the silver halide emulsion or emulsions of the laminate are appropriately protected from incident radiation at one major surface by the opaque layer or layers 20 and at the remaining major surface by opaque processing composition 12 as further described hereinafter. If the illustrated binding sheets are also opaque as stated above, edge leakage of actinic radiation incident on the emulsion or emulsions will also be prevented. The selected opaque layer or layers 20, however, should be one providing a background suitable forviewing the color transfer image formed in the dyeable polymeric layer, In general, while substantially any permeable opaque layer may be employed, it is preferred that a layer be selected that will not interfere with the color integrity of the dye transfer image as viewed by the observerand, most preferably, a layer which is aesthetically pleasing to the viewer and does not provide a background degrading, ordetracting from, the information content of the image. Particularly desirable opaque layers will be those providing a white background for viewing the transfer image and, specifically, those adapted to be employed to provide a background for reflection photographic prints and especially, those layers possissing the optical properties desired for reflectance of incident radiation.

The opaque layer may comprise substantially any opacifying agent compatible with the photographic system such as, for example, barium sulfate, zinc oxide, titanium dioxide, barium stearate, silver flake, silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodium zirconium sulfate, kaolin, mica and the like, which may be distributed in a permeable polymeric matrix or binder such as, for example, gelatin, polyvinyl alcohol, and the like.

A particularly preferred opaque layer comprises titanium dioxide selected for its highly effective reflection properties. In general, a coating composition such as hydroxyethylcellulose, containing sufficient titanium dioxide to provide a percent reflectance in the range of 85 to 99 percent will be employed. In the most preferred embodiments, acceptable percent reflectance near the lower end of this range will be on the order of percent.

Where it is desired to increase the opacifying capacity of a layer containing, for example, titanium dioxide, beyond that ordinarily obtained, an additional opacifying agent such as carbon black may be provided in the layer, in a concentration, for example, of about 1 part carbon black to to 500 parts titanium dioxide. Preferably, however, such additional opacifying capacity will be provided by constituting the opacifying layer as a plurality of more or less discretelayers, the layer next adjacent the transparent support comprising a reflection layer and the succeeding layer or layers comprising one or more opacifying agents possessing greater opacifying capability than that ordinarily obtained from the reflecting agent or agents employed.

The opacifying agent dispersed in processing composition 12 may be any of the multiplicity of such agents known in the art such as carbon black, iron oxide, titanium (III) oxide, titanium (III) hydroxide, and the like. Preferably, the agent or agents should be selected from those which possess the maximum opacifying capacity per unit weight, are photographically nondeleterious and are substantially non-diffusible throughout the film unit subsequent to distribution. A particularly preferred agent has been found to comprise carbon black employed in a concentration effective to provide the opacity required to prevent undesired physical fogging of the emulsion formulations selected and employed by radiation transmitted through the spread processing composition.

In the performance of a diffusion transfer multicolor process employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 13, incident on the outer or forward surface of sheet 25 and transmitted therethrough to the underlying photosensitive laminate.

Subsequent to exposure, film unit 10 is processed by moving it relative to and between a pair of pressureapplying members in order to apply compressive pressure to rupturable container 11 to effect rupture of longitudinal seal 28 and distribution of processing composition 12, containing an opacifying agent and having a pH at which the cyan, magenta and yellow dye developers are soluble and diffusible, intermediate and in contact with the facing surfaces of transparent sheet 25 and blue-sensitive silver halide emulsion layer 15.

Processing composition 12 permeates emulsion layers l5, l7 and 19 to initiate development of the latent images contained in the respective emulsions. The cyan, magenta and yellow dye developers of layers 15, 17, and 19 are immobilized as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nondiffusible oxidized form, thereby providing imagewise distributions of mobile, soluble and diffusible cyan, magenta and yellow dye developers, as a function of the point-to-point degree of exposure of their associated emulsions. At least part of the imagewose distributions of mobile cyan, magenta and yellow dye developer, transfer by diffusion to processing composition permeable polymeric layer 21 to provide a mutlicolor dye transfer image in that layer. Subsequent to substantial transfer image formation, a sufficient portion of the ions comprising aqueous composition 12 transfer, by diffusion, through permeable imagereceiving layer 21, permeable spacer layer 22 and to neutral izing layer 23 whereby solution 12 decreases in pH, as a function of neutralization, to a pH at which the cyan, magenta and yellow dye developers, in the reduced form, are substnatially insoluble and nondiffusible, to provide thereby a stable mutlicolor dye transfer image viewable through dimensionally stable transparent layer 24.

The present invention will be further illustrated and detailed in conjunction with the following illustrative constructions which set out representative constructions of photographic film units employed in the practice of this invention and which, however, are not limited to the detailsherein set forth and are intended to be illustrative.

Film units similar to that set forth in the drawings may be prepared, for example, by coating, in succession, on a transparent cellulose triacetate film base:

1 the partial butyl ester of polyethylene/maleic anhydride copolymer prepared by refluxing for 14 hours, about 300 grams of high viscosity poly- (ethylene/maleic anhydride), about 140 grams of n-butyl alcohol and about 1 cc. of 85 percent phosphoric acid to provide a polymeric acid layer approximately 0.75 mil. thick;

2. a solution of hydroxy propyl cellulose in water to provide a polymeric spacer layer approximately 0.075 mils. thick;

3. a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of approximately 600 mgs./ft. to provide a polymeric imagereceiving layer approximately 0.40 mils. thick;

4. a layer of titanium dioxide dispersed in hydroxyethyl cellulose and coated at a coverage of about 1200 mgsjft. of titanium dioxide and about 30 mgs./ft. of hydroxyethyl cellulose;

5. a layer of gelatin coated at a coverage of about 200 mgs./ft.

6. a layer of the acrylic latex sold by Rohm and Haas Co., Philadelphia, Pennsylvania under the trade designation Rhoplex AC-6l coated at a coverage of about 110 mgs./ft.

7. a layer of carbon black dispersed in hydroxyethyl cellulose coated at a coverage of about 150 mgs./ft. carbon black and about 3.0 mgs./ft. hydroxyethyl cellulose;

8. a layer of the cyan dye developer l,4-bis-(B- [hydroquinonyl-a-methyl]-ethyl-amino)-5,8- dihydroxy-anthraquinone and carbon black dispersed in gelatin and coated at a coverage of about 50 mgs./ft. of dye, about 180 mgs./ft." of carbon black and about 63 mgsJft. of gelatin;

9. A red-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 120 mgs./ft. of silver and about 22 mgsJft. of gelatin;

10. a layer of Rhoplex AC-6l coated at a coverage of about 80 mgsJftF;

11. a layer of the magenta dye developer 4- isopropoxy-Z-[p-(B-hydroquinonyl ethyl)- phenylazo]-naphthalene-l-ethoxy acetate dispersed in a green-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 80 m'gs./ft. of dye, about 110 mgs./ft of silver and about 150 mgs./ft. of gelatin;

12. a layer of the last-mentioned magenta dye developer dispersed in gelatin at a coverage of about 20 mgs./ft. of dye and about 30 mgsJft. gelatin;

13. a layer of Rhoplex AC-61 coated at a coverage of about mgs./ft.

14. a layer of the yellow dye developer 4-(p-[- hydroquinonyl ethyl]-phenylazo)-3-(N-nhexylcarboxamido )-l-phenyl-5 -phazolon dispersed in gelatin and coated at a coverage of about mgs./ft. of dye and about 175 mgs./ft. of gelatin;

15. a blue-sensitive gelatino silver iodobromide emulsion coated at a coverage of about mgs./ft. of silver and about 28 mgs./ft. of gelatin; and

16. a layer containing 4 '-methylphenyl hydroquinone dispersed in gelatin at a coverage of about 20 mgs./ft. of 4'-methylphenyl hydroquinone and about 30 mgs./ft. of gelatin.

Transparent cellulose triacetate film base may then be superposed on the external surface of coating No. 16 and the two components then taped together, in composite form, at their respective edges by means of opaque pressure-sensitive binding tape extending around, in contact with, and over the edges of the resultant film unit.

A rupturable container comprising an outer layer of paper, an intermediate layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution comprising:

Water l00 cc. Potassium hydroxide l 1.2 gins. Hydroxyethyl cellulose (high 3.4 gms. viscosity) [commercially available from Hercules Powder Co., Wilmington, Delaware, under the trade name Natrasol 250} N-benzyi-cr-picolinium bromide l.5 gms. Benzotriazole 1.0 gm. Carbon black 6.4 grns.

may then be attached to the leading edge of each of the assemblages by a binding sheet or sheets including, for example, a pressure-sensitive adhesive for interconnecting the respective containers and laminates. The container is attached such taht upon the application of compressive pressure thereto, the containers marginal seal will be ruptured and its contents will be distributed intermediate the cellulose triacetate sheet and the 4'- methylphenyl hydroquinone-containing layer.

The pH and solvent concentration of the alkaline processing solution initially employed must be a pH at which the dye developers employed are diffusible. Although it has been found that the specific pH to be employed must be readily determined empirically for any dye developer, or group of dye developers, most particularly desirable dye developers are soluble at pHs above 9 and relatively insoluble at pHs below 9, in reduced form, and the system can be readily belanced accordingly for such dye developers. in addition, the processing composition, as previously noted in the preferred embodiment will include a film-forming viscosity-increasing agent or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structurally stable layer of the laminate subsequent to distribution. However, it is not necessarythat' such agent be employed as a component of the composition and in the latter instance, it will be preferred that the concentration of solvent, that is, water, etc., comprising the composition be the minimum amount necessary to conduct the desired transfer process in order not to adversely effect the structural integrity of the laminate and insure that the layers forming the laminate can readily accommodate and dissipate the solvent during processing and drying without effecting undesirable dimensional changes in the layers forming the laminate.

Neutralizing means, for example, a neutralizing layer such as a polymeric acid layer of the type discussed above, are incorporated in the film unit of the present invention to provide for reduction of the alkalinity of the processing solution from a pH at which the dyes are soluble to a pH below the pH of the agent at which the dyes are substantially non-diffusible, in order to advantageously further stabilize and optimize reflectively of the dye transfer image. In such instance, the neutralizing layer may comprise a particulate acid reacting reagent disposed within the film unit in a polymeric acid layer. Such a polymeric acid layer, for example, may be approximately 0.3 to 1.5 mils in thickness, is positioned intermediate the transparent support and imagereceiving layer, and/or the opaque support and next adjacent emulsion/dye u-nit layer. The film unit may also contain a polymeric spacer or barrier layer, for example, approximately 0.1 to 0.7 mul. in thickness next adjacent the polymeric acid layer on the side thereof opposite the respective support layer as previously described. While the neutralizing layer has been shown to be disposed on the side of receiving layer opposed from the photosensitive strata, it may, if desired, be located elsewhere in the film unit and/or on the transparent sheet, e.g., on the surface of sheet 25 facing laminate 13.

The neutralizing layer so employed may comprise a polymeric acid layer such as one of the type disclosed in U. S. Pat. No. 3,362,819. Most preferably, an inert timing or spacer layer is associated with the neutralizing layer for reasons which are set forth in this patent and which will be discussed hereinafter.

As set forth in the last-mentioned patent, the polymeric acid layer may comprise polymers which contain acid groups such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals such as sodium, potassium etc., or with organic bases, particularly quaternary ammonium bases such as tetramethyl ammonium hydroxide, or potentially acidyielding groups such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, of course, retained in the polymer layer. In the preferred embodiments disclosed, the polymer contains free carboxyl groups and the transfer processing composition employed contains a large concentration of sodium and/or potassium ions. The acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and being capable of forming water-soluble sodium and/or potassium salts. Polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to imbibition, may also be employed, while the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids set forth in the application, mention may be made of dibasic acid half-ester derivatives' of cellulose which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogren phthalate, cellulose actate hydrogen gluturate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives or cellulose modified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo substituted aldehydes, e.g., o-, m-, or p-benzaldehyde sulfonic acid or carboxylic acid; partial esters of ehtylene/maleic anydride copolymers; partial esters of methyl-vinyl ether/maleic anhydride copolymers; etc.

As previously noted, the pH of the processing composition preferably is of the order of at least 12 to 14. The polymer layer is disclosed to contain at least sufficient acid groups to effect a reduction in the pH of the image layer from a pH of about 12 to 14 to a pH at least 11 or lower at the end of the imbibition period, and preferably to a pH of about 5 to 8 within a short time after imbibition, thus requiring, of course, that the action of the polymeric acid be accurately so controlled as not to interfere with either development of the negative or image transfer of unoxidized dye developers. For this reason, the pH of the image layer must be kept at a functional transfer level, for example, 12 to 14 until the dye image has been formed after which the pH is reduced very rapidly to a pH below that at which dye transfer may be accomplished, for example, at least about 1 1 and preferably about 9 to 10 Unoxidized dye developers containing hydroquinonyl developing radicals diffuse from the negative to the positive as the sodium or other alkali salt. The diffusion rate of such dye image-forming components thus is at least partly a function of the alkali concentration, and it is necessary that the pH of the image layer remain on the order of, for example, 12 to 14 until transfer of the necessary quantity of dye has been accomplished. Thesubsequent pH reduction, in addition to its desirable effect upon image light stability, serves a highly valuable photographic function by substantially terminating further dye transfer.

The inert spacer layer of the last-mentioned patent, for example, an inert spacer layer comprising polyvinyl alcohol or gelatin, acts to time control the pH reduction by the polymeric acid layer. This timing is disclosed to be a function of the rate at which the alkali diffuses through the inert spacer layer. It is there stated to have been found that the pH does not drop until the alkali has passed through the spacer layer, i.e., the pH is not reduced to any significant extent by the mere diffusion into the interlayer, but the pH drops quite rapidly once the alkali diffuses through the spacer layer.

As disclosed in aforementioned U. S. Pat. No. 3,362,819, the presence of an inert spacer layer was found to be effective in evening out the various reaction rates over a wide range of temperatures, for example, by preventing premature pH reduction when imbibition is effected at temperatures above room temperature, for example, at to F. By providing an inert spacer layer, that application discloses that the rate at which alkali is available for capture in the polymeric acid layer becomes a function of the alkali diffusion rates. Suitable spacer layers of this description are disclosed in the aforementioned U. S. Pat. No. 3,362,819 and in others, including U. S. Pat. Nos.

3,419,389; 3,521,893; 3,433,633; and 3,575,701.

Although the preceding description of the invention has been couched in terms of the preferred photosensitive component construction wherein at least two selectively sensitized photosensitive strata are in continguous planar relationship and, specifically, in terms of the preferred tripack type structure comprising a reDlsensitive silver halide emulsion stratum, a greensensitive silver halide emulsion stratum and a bluesensitive silver halide emulsion stratum having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer, the photosensitive component of the film unit may comprise at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen wherein each of the minute photosensitive elements has associated therewith, for example, an appropriate dye image-forming material in or behind its respective silver halide emulsion portion. In general, a suitable photosensitive screen may comprise minute red-sensitized emulsion elements, minute green-sensitized emulsion elements and minute bluesensitized emulsion elements arranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, for ecample, a cyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dye image-providing material and the use of a mixture of, for example, dye developers adapted to provide a black-and-white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportioned such that the colors combine to provide black.

Where in the specification, the expression positive image has been used, this expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive emulsion layers. As an example of an alternative meaning for positive image," assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case, the latent image in the photosensitive emulsion layers will be a positive and the dye image produced on the image-carrying layer will be a negative. The expression positive image is intended to cover such as image produced onflthe image-carrying layer.

In addition to the described essential layers, it will be recognized that the film, may also contain one or more subcoats or layers, whichQin turn, may contain one or more additives such as plasticizers, intermediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composite of two or more strata of the same, or different, components and which may be contiguous, or separated from, each other, for example, two or more neutralizing layers or the like.

In addition, the polymeric neutralizing layer disclosed to be optionally disposed, in a preferred embodiment, intermediate the dimensionally stable transparent support and next adjacent essential layer may, where desired, by disposed carried by the transparent sheet element on th surface of that element next adjacent the photosensitive laminate and adapted to effect the stated in situ process modulation of the environmental pl-I, subsequent to substantial dye transfer image formation. In such structure, the pH modulating acidic component may be appropriately insulated to a substantial extent from deleterious interaction with the remainder of the photographic system during storage, exposure and initial processing of the film unit by means of, for example, a polymeric diffus on control barrier or spacer timing layer of the general type and design discussed above and may be employed alone or in combination with the polymeric neutralizing layer discussed hereinbefore. The in situ process modulation referred to may also optimally be in whole or in part accomplished by the employ ent of particulate acidic material distributed within the film unit and selectively available to effect the desired pH reduction in accordance with techniques disclosed in the copending U. S. Pat. No. 3,576,625 incorporated by reference herein. next adjacent essential layer may, where desired, by disposed carried by the transparent sheet element on th surface of that element next adjacent the photosensitive laminate and adapted to effect the stated in situ process modulation of the environmental pH, subsequent to substantial dye transfer image formation. In such structure, the pH modulating acidic component may be appropriately insulated to a substantial extent from deleterious interaction with the remainder of the photographic system during storage, exposure and initial processing of the film unit by means of, for example, a polymeric diffus on control barrier or spacer timing layer of the general type and design discussed above and may be employed alone or in combination with the polymeric neutralizing layer discussed hereinbefore. The in situ process modulation referred to may also optimally be in whole or in part accomplished by the employ ent of particulate acidic material distributed within the film unit and selectively available to effect the desired pH reduction in accordance with techniques disclosed in the copending U. S. Pat. No. 3,576,625 incorporated by reference herein.

Reference is now made to FIGS. 1, 9 and 10 of the drawings wherein there are illustrated film units and an assemblage of film units in the form of a film pack. As was heretofore mentioned, each film unit 10 includes a sheet 31 (hereinafter referred'to as a leader sheet) having a leading end section designated 38 and a trailing end section 40 at which the leader sheet 31 is coupled with the film unit near theleading end thereof. Leader sheet 31 including leading and trailing end sections 38 and 40 is approximately equal in width to the film unit 10 and leading end section 38 of Reference is now made to FIGS. l, 9 and 10. of the drawings wherein there are illustrated film units and an assemblage of film units in the form of a film pack. As was heretofore mentioned, each film unit 10 includes a sheet 31 (hereinafter referred to as a leader sheet) having a leading end section designated 38 and a trailing end section 40 at which the leader sheet 31 is coupled with the film unit near theleading end thereof. Leader sheet 31 including leading and trailing end sections 38 and 40 is approximately equal in width to the film unit 10 and leading end section 38 of each leader sheet 31 is secured to the trailing end of the next preceding film unit or, in the case of the first film unit, to the cover sheet, preferably near the trailing end section of the preceding element (cover sheet or film unit).

The length of leader sheet 31 between its leading edge attachment to one film unit and the trailing edge to the next succeedin film unit is substantially equal to the length of the film units between their leading and trailing edges; and the connected film units and leaders are arranged in zig-zag folded relation. each leader sheet 31 is secured to the trailing end of the next preceding film unit or, in the case of the first film unit, to the cover sheet, preferably near the trailing end section of the preceding element (cover sheet or film unit). The length of leader sheet 31 between its leading edge attachment to one film unit and the trailing edge to the next succeedin film unit is substantially equal to the length of the film units between their leading and trailing edges; and the connected film units and leaders are arranged in zig-zag folded relation.

A film pack or assemblage of film units embodying the invention is show in FIGS. 8 and 9 of the drawings. This film pack, designated 44, comprises all of the components and structure including pressure-applying means required to produce a plurality of diffusion transfer process color prints. Film pack 44 comprises a generally parallelepiped-shaped container or box 46 for holding and enclosing a plurality of film units 10 arranged in stacked relation. Container 46 is shown as comprising a forward wall 48, side walls 50, a trailing end wall 52, alead ing end wall 54, and a rear wall 56 and is preferably formed of plastic material that is at least semi-rigid and adapted to conventional modeling techniques. Forward wall 48 is provided with a generally rectangular exposur aperture 58 for transmitting light for exposing the forwardmost of the film units carried in stacked relation within the container. Leading end wall 54 is provided with a generally rectangular withdrawal slot or exit opening 60 the forward edge of which is defined by forward wall 48 and through which film units 10 carried by the container are adapted to be withdrawn one at a time following A film pack or assemblage of film units 10 embodying the invention is show in FIGS. 8 and 9 of the drawings. This film pack, designated 44, comprises all of the components and structure including pressure-applying means required to produce a plurality of diffusion transfer process color prints. Film pack 44 comprises a generally parallelepiped-shaped container or box 46 for holding and enclosing a plurality of film units 10 arranged in stacked relation. Container 46 is shown as comprising a forward wall 48, side walls 50, a trailing end wall 52, a leadinjg end wall 54, and a rear wall 56 and is preferably formed of plastic material that is at least semi-rigid and adapted to conventional modeling techniques. Forward wall 48 is provided with a generally rectangular exposur aperture 58 for transmitting light for exposing the forwardmost of the film units carried in stacked relation within the container. Leading end wall 54 is provided with a generally rectangular withdrawal slot or exit opening 60 the forward edge of which is defined by forward wall 48 and through which film unitslO carried by the container are adapted to be withdrawn one at a time following exposure. In order to help insure that only on film unit at a time passes through opening 60, restraining means in the form of one or more projections or extensions 62 of end wall 54 may be provided. Projections 62, which as illustrated are integral parts of end wall 54, project forwardly part way across opening 60 to positions whereat they sufficiently obstruct th opening to the extent that they must be deformed in order to permit the passage of the forwardmost film unit in the stack, that is, the film unit positioned for exposure across aperture 58 against forward wall 48. Projections 62 comprise a resilient construction such that as th leading film unit is withdrawn through opening 60, the leading edge of the film unit will engage and deflect projections 62 outward sufficiently to permit the forward film unit only to move through slot 60, while preventing the next succeeding film unit from moving through the slot. exposure. In order to help insure that only on film unit at a time passes through opening 60, restraining means in the form of one or more projections or extensions 62 of end wall 54 may be provided. Projections 62, which as illustrated are integral parts of end wall 54, project forwardly part way across opening 60 to positions whereat they sufficiently obstruct th opening to the extent that they must be deformed in order to permit the passage of the forwardmost film unit in the stack, that is, the film unit positioned for exposure across aperture 58 against forward wall 48. Projections 62 comprise a resilient construction such that as the leading film unit is withdrawn through opening 60, the leading edge of the film unit will engage and deflect projections 62 outward sufficiently to permit the forward film unit only to move through slot 60, while preventing the next succeeding film unit from moving through the slot.

The film pack of the invention is initially provided with a dark slide or cover sheet 64 formed of an actinic light-impermeable sheet material for preventing admission of light through exposure aperture 58 prior to loading of the film pack into a camera or attachment of the film pack to the rear of a camera. Cover sheet 64 includes a section at least coextensive in area with forward wall 48 for preventing the admission of light and a leading end section 66 which may be tapered, as shown, extending from the film pack and providing a leader which may be grasped for manually withdrawing the cover sheet from the film pack to permit exposure of film units arranged in stacked relation underlying the exposure opening and cover sheet. A lip 68 The film pack of the invention is initially provided with a dark slide or cover sheet 64 formed of an actinic light-impermeable sheet material for preventing admission of light through exposure aperture 58 prior to loading of the film pack into a camera or attachment of the film pack to the rear of a camera. Cover sheet 64 includes a section at least coextensive in area with forward wall 48 for preventing the admission of light and a leading end section 66 which may be tapered, as

shown, extending from the film pack and providing a leader which may be grasped for manually withdrawing 'the cover sheet from the film pack to permit exposure of film units arranged in stacked relation underlying the exposure opening and cover sheet. A lip 68 is provided on forward wall 48 surrounding opening 58 for cooperating with the camera to properly locate the film pack and exposure opening therein with respect to the exposure systems of the camera and in instances where the film pack is coupled to the rear of the camera rather than being completely enclosed therein, lip 68 also cooperates to form a light-tight seal between the interior of the camera and the interior of the film pack container. is provided on forward wall 48 surrounding opening 58 for cooperating with the camera to properly locate the film pack and exposure opening therein with respect to the exposure systems of the camera and in instances where the film pack is coupled to the rear of the camera rather than being completely enclosed therein, lip 68 also cooperates to form a light-tight seal between the interior of the camera and the interior of the film pack container.

As previously noted, the film units are arranged in stacked relation between the forward and rear walls of the film pack with sheets 25 facing forwardly and the exposure areas of the film units aligned with exposure opening 58. Means are provided for resiliently biasing the film units 10 and cover sheet 64 forwardly against the rear surface of forward wall 48 to light seal the exposure aperture when the cover sheet is in place and following cover sheet removal, locate the forwardmost film unit in proper position for exposure in the image plane of the camera, i.e., against the rear surface of forward wall 48. These means include a spring and pressure plate assembly designated 70, preferably formed of resilient sheet metal and including a generally rectangular frame 72 for engaging and supporting the rearwardmost film unit and a transverse portion 74 from which extend rearwardly biased spring sections 76 engaged with the rear wall 56 of the film pack for biasing frame 72 and the film units supported thereby, forwardly toward forward wall 48.

As previously noted, the film units 10 are arranged in stacked relation between the forward and rear walls of the film pack with sheets 25 facing forwardly and the exposure areas of the film units aligned with exposure opening 58. Means are provided for resiliently biasing the film units 10 and cover sheet 64 forwardly against the rear surface of forward wall 48 to light seal the exposure aperture when the cover sheet is in place and following cover sheet removal, locate the forwardmost film unit in proper position for exposure in the image plane of the camera, i.e., against the rear surface of forward wall 48. These means include a spring and pressure plate assembly designated 70, preferably formed of resilient sheet metal and including a generally rectangular frame 72 for engaging and supporting the rearwardmost film unit and a transverse portion 74 from which extend rearwardly biased spring sections 76 engaged with the rear wall 56 of the film pack for biasing frame 72 and the film units supported thereby, forwardly toward forward wall 48.

As previously noted, each film unit 10 includes a leader 31 attached at its trailing end 40 to the forward surface of the film unit near the leading end thereof. The film units and leaders are arranged in the film packcontainer I As previously noted, each film unit 10 includes a leader 3] attached at its trailing end 40 to the forward surface of the film unit near the leading end thereof. The film units and leaders are arranged in the film pack container with the trailing end of each leader 31 folded back upon itself so that the leader extends towar d the trailing end of the film unit and pack container between the forward surface of the film unit of which it is a component and the rear surface of the cover sheet 64 (in the case of the forwardmost film unit) or the rear surface of the preceding film unit next adjacent forward wall 48 and exposure aperture 58. The leading end 38 of each film unit is folded forwardly upon itself and attached to the rear surface of the component, i.e., cover sheet 64 or film unit 10, located next adjacent the forward wall and is secured to said component near the trailing end thereof. Thus the cover sheet 64 and sucend of each leader 3 1 folded back fip on itself so that the leader extends toward the trailing end of the film unit and pack container between the forward surface of the film unit of which it is a component and the rear surface of the cover sheet 64 (in the case of the forwardmost film unit) or the rear surface of the preceding film unit next adjacent forward wall 48 and exposure aperture 58. The leading end 38 of each film unit is folded forwardly upon itself and attached to the rear surface of the component, i.e., cover sheet 64 or film unit 10, located next adjacent the forward wall and is secured to said component near the trailing end thereof. Thus the cover sheet 64 and succession of film units 10 are joined by leaders 31, each of which extends from the trailing end of the component to the leading end of the next component (film unit) to be withdrawn from the pack. The leaders 31 are folded in zigzag fashion to provide a stack comprising cover sheet 64, a leader 31, a film unit 10, another leader 31, and so forth. Each leader 31 may be weakened by perforations, precutting, or the like so that the portion of a leade attached to a film unit within the pack and extending from the pack to provide a leader for withdrawing the last mentioned film unit may be severed fron the portion of the leader attached to the preceeding component, i.e., cover sheet 64 or film unit 10. may be weakened by perforations, precutting, or the like so that the portion of a leade attached to a film unit within the pack and extending from the pack to provide-a leader for withdrawing the last mentioned film unit may be severed fron the portion of the leader attached to the preceeding component, i.e., cover sheet 64 or film unit 10.

As a general rule, in diffusion transfer color imageforming processes and particularly in transfer processes which result in the formation of a color reflection print and in which the processing liquid is distributed in a layer between photosensitive and image-receiving layers, the continuity, thickness, and uniformity of the layer of processing liquid is very critical. Spreading of the processing.

As a general rule, in diffusion transfer color imageforming processes and particularly in transfer processes which result in the formation of a color reflection print andin which the processing liquid is distributed in a layer between photosensitive and image-receiving layers, the continuity, thickness, and uniformity of the layer of processing liquid is very critical. Spreading of the processing liquid as a layer possessing the required tolerances, particularly when the quantity of excess processing liquid is minimized, requires a carefully designed and constructed liquid spreading system that may be very complex and extremely expensive, and certainly too complex and expensive to be incorporated in a film pack and/or to be discarded after the filrn units of a film pack have been expended liquid as a layer possessing the required tolerances, particularly when the quantity of excess processing liquid is minimized, requires a carefully designed and constructed liquid spreading system that may be very complex and extremely expensive, and certainly too complex and expensive to be incorporated in a film pack and/or to be discarded after the film units of a film pack have been expended The reasons for this criticality of liquid spreading include, but are not limited to, the fact that the layer of liquid may be required to mask the image in the photosensitive layer and/or to provide a background for the visible tansfer print; the liquid contains an opacifying agent for preventing exposure of the photosensitive material upon withdrawal of the film unit from the camera; and being spread substantially in direct contact with the photosensitive and image-receiving layers, it is absorbed almost immediately as it is spread so than any variations in thickness or discontinuities in distribution result in corresponding variations in liquid absorption and diffusion transfer image formation.

The reasons for this criticality of liquid spreading include, but are 'not limited to, the fact that the layer of liquid may be required to mask the image in the photosensitive layer and/or to provide a background for the visible tansfer print; the liquid contains an opacifying agent for preventing exposure of the photosensitive material upon withdrawal of the film unit from the camera; and being spread substantially in direct contact with the photosensitive and image-receiving layers, it is absorbed almost immediately as it is spread so than any variations in thickness or discontinuities in distribution result in corresponding variations in liquid absorption and diffusion transfer image formation.

The uniformity of processing liquid distribution is especially critical in the production of color reflection prints by a dye designed to remain intact prior to, during, and subsequent to exposure and processing in ,which the processing liquid is spread between photosensitive and image-receiving layers; and the film unit is designed to be withdrawn directly from the spread system and/or camera into th light where the majority of transfer image-forming processing occurs. Film units of this type are disclosed in n umerous prior art patents including many of the patents cited hereinbefore and particularly film units such as disclosed in U.S. Pat. Nos. 2,983,606, 3,053,659, 3,415,644,

The uniformity of processing liquid distribution is especially critical in the production of color reflection prints by a dye designed to remain intact prior to, during, and subsequent to exposure and processing in which the processing liquid is spread between photosensitive and image-receiving layers; and the film unit is designed to be withdrawn directly from the spread system and/or camera into th light where the majority of transfer image-forming processing occurs. Film units of this type are disclosed in n umerous prior art patents including many of the patents cited hereinbefore and particularly film units such as disclosed in U.S. Pat.

Nos. 2,983,606, 3,053,659, 3,415,644, 3,415,645, 3,473,925, 3,578,540, 3,585,028, 3,607,285, 3,615,421, 3,615,436, 3,615,540, 3,619,192, and 3,619,193. 3,415,645, 3,473,925, 3,578,540, 3,585,028, 3,607,285, 3,615,421, 3,615,436,

3,615,540, 3,619,192, and 3,619,193.

However, it has been found that uniformity of liquid distribution is not critical in processing of the type described in the aforementioned U.S. Pat. Nos. 2,983,606, 3,594,164, and 3,594,165, in which the processing liquid is spread between a laminate including both the photosensitive and image-receiving layers and an other layer which may merely aid in spreading of the processing liquid. [t has been found that substantial variations in the liquid layer spread thickness and even small holidays can be tolerated since they have no observable effect on the quality of the positive transfer print. This is due in part to the fact that there are more layers for the liquid to penetrate affording an opportunity for uniform absorption of the processing liquid by the photosensitive and image-recording layers.

However, it has been found that uniformity of liquid distribution is not critical in processing of the type described in the aforementioned U.S. Pat. Nos. 2,983,606, 3,594,164, and 3,594,165, in which the processing liquid is spread between a laminate including both the photosensitive and image-receiving layers and an other layer which may merely aid in spreading of the processing liquid. It has been found that substantial variations in the liquid layer spread thickness and even small holidays can be tolerated since they have no observable effect on the quality of the positive transfer print. This is due in part to the fact that there are more layers for the liquid to penetrate affording an opportunity for uniform absorption of the processing liquid by the photosensitive and image-recording layers.

The permissible variations and liquid spread thickness and continuity within the aforementioned particular type of film unit adapted to produce a diffusion transfer process color reflection print are such that is is now possible to employ a relatively simple and inexpensive liquid spreading system. Such systems are sufficiently inexpensive and suitable for incorporation in an assemblage of film units or film packs intended to be expendable and to be discarded following exposure and processing of the film units.

The permissible variations and liquid spread thickness and continuity within the aforementioned particular type of film unit adapted to produce a diffusion transfer process color reflection print are such that is is now possible to employ a relatively simple and inexpensive liquid spreading system. Such systems are sufficiently inexpensive and suitable for incorporation in an assemblage of film units or film packs intended to be expendable and to be discarded following exposure and processing of the film units.

In accordance with the invention, film pack 44' includes means for compressively engaging each film unit as it is withdrawn therefrom following exposure, to rupture container 11 causing the discharge of its liquid contents between sheet 25 and layer 13 and spread the liquid contents of the container as a thin layer between the aforementioned layer and sheet. As shown in FIGS. 8 and 9, these pressure-applying In accordance with the invention, film pack 44 includes means for compressively engaging each film unit as it is withdrawn therefrom following exposure, to rupture container 11 causing the discharge of its liquid contents between sheet 25 and layer 13 and spread the liquid contents of the container as a thin layer betwee the aforementioned layer and sheet. As shown in FIGS. 8 and 9, these pressure-applying means take the form of an integral pressure-applying unit or device coupled to box 46 at the leading end thereof. Pressureapplying device 70 is preferably formed of a sheet material such as metal which is both structurally strong and rigid while having flexibility sufficient to accommodate the varying thickness of a film unit as the latter is withdrawn from the film pack. Device 70 is shown as having a generally parallelepiped shape including a forward wall 72, rear wall 74 and side walls 76 adapted to encompass the leading end portion of the forward, rear and side walls of container 46, to provide additional strength and rigidity and to cooperate in retaining pressure-applying device 70 on box 46 as a component of film pack 44. Forward wall 72 is provided with a rearwardly extending dependent lip 76 and rear wall 74 is provided with a forwardly extending dependent lip 78. The spreading device includes a leading end wall including a forward section 80 and a rear section 82 separated from one another by a withdrawal opening or passage. Forward section 80 and rear section 82 include edge portions rolled upon themselves to form cylinders or pressure-applying members designated means take the form of an integral pressure-applying unit or device 70 coupled to box 46 at the leading end thereof. Pressure-applying device 70 is preferably formed of a sheet material such as metal which is both structurally strong and rigid while having flexibility sufficient to accommodate the varying thickness of a film unit as the latter is withdrawn from the film pack. Device 70 is shown as having a generally parallelepiped shape including a forward wall 72, rear wall 74 and side walls 76 adapted to encompass the leadingend portion of the forward, rear and side walls of container 46, to provide additional strength and rigidity and to cooperate in retaining pressure-applying device 70 on box 46 as a component of film pack 44. Forward wall 72 is provided with a rearwardly extending dependent lip 76 and rear wall 74 is provided with a forwardly extending dependent lip 78. The spreading device includes a leading end wall including a forward section 80 and a rear section 82 separated from one another by a withdrawal opening or passage. Forward section 80 and rear section 82 include edge portions rolled upon themselves to form cylinders or pressure-applying members designated 90 and 92 respectively, having substantial resistance to flexure or bending and adapted to function as a pair of pressureapplying members. 90 and 92 respectively, having substantial resistance to flexure or bending and adapted to function as a pair of pressure-applying members.

Lips 76 and 78 are engaged with ridges 86 and 88 formed on the leading end portions of forward wall 48 and rear wall 56 respectively, of the film pack container 46. Ridges 86 and 88 are inclined or tapered'toward the leading end of the film unit to facilitate coupling of the pressure-applying device 70 to the film pack container simply by pressing the pressureapplying device onto the end of the container slightly Lips 76 and 78 are engaged with ridges 86 and 88 formed on the leading end portions of forward wall 48 and rear wall 56- respectively, of the film pack container 46. Ridges 86 and 88 are inclined or tapered toward the leading end of the film unit to facilitate coupling of the pressure'applying device 70 to the film pack container simply by pressing the pressureapplying device onto the end of the container slightly deforming the forward and rear walls of the container and/or pressure-applying device as required to permit lips 76 and 78 to pass over the ridges 86 and 88 into the position shown in FIG.'9 in which the rear portion of forward wall 82 is disposed against end wall 54 of the film pack container. deforming the forward and rear walls of the container and/or pressure-applying device as required to permit lips 76 and 78 to pass over the ridges 86 and 88 into the position shown in FIG. 9 in which the rear portion of forward wall 82 is disposed against end wall 54 of the film pack container.

As previously noted, and as will be apparent from the drawings, the minimum or compressed thickness of the film unit will vary throughout the length of the film unit so that the depth of the gap or passage 84 between pressure-applying members and 92 should be variable so that the pressure-applying members apply compressive pressure regardless of the variation in the film unit thickness. To facilitate relative movements of the cylindrical pressure-applying members which are preferably located with their axis parallel and coplanar, rear portion 82 is formed with slits 94 at the ends of cylindrical pressure-applying members 92 to facilitate movement of member 92 relative to pressure-applying member 90 toward and away from the latter.

As previously noted, and as will be apparent from the drawings, the minimum or compressed thickness of the film unit will vary throughout the length of the film unit so that the depth of the gap or passage 84 between pressure-applying members 90 and 92 should be variable so that the pressure-applying members apply compressive pressure regardless of the variation in the film unit thickness. To facilitate relative movements of the cylindrical pressure-applying members which are preferably located with their axis parallel and coplanar, rear portion 82 is formed with slits 94 at the ends of cylindrical pressure-applying members 92 to facilitate movement of member 92 relative to pressure-applying member 90 toward and away from the latter.

While a zig-zag folded arrangement of interconnected leaders and film units is illustrated, it should be understood that means other than those shown in the drawings may be provided for assisting in the manual withdrawal of the] film unit, one at a time, from the film pack between the pressure-applying members. Such means are disclosed, for example, in U.S. Pat. Nos 2,903,951, 2,909,977, and 2,946,270. Other systems in which a leader of one film unit is withdrawn from th pack to a position at which it can be gripped by and in response to withdrawal of the previous film unit or the cover sheet are also well known in the art and ca be employed in placeof the leader system shown.

While a zig-zag folded arrangement of interconnected leaders and film units is illustrated, it should be understood that means other than those shown in the drawings may be provided for assisting in the manual withdrawal of thel film unit, one at a time, from the film pack between the pressure-applying members. Such means are disclosed, for example, in US. Pat. No.5 2,903,951, 2,909,977, and 2,946,270. Other systems in which a leader of one film unit is withdrawn from th pack to a position at which it can be gripped by and in response to withdrawal of the previous film unit or the cover sheet are also well known in the art and ca be employed in placeof the leader system shown.

It will be seen from the foregoing that the invention provides a simple and inexpensive film pack structure including all 0 the components required to produce a plurality of color prints; anel that such prints are'produced simply and easily by manually withdrawing exposed film units one at a time from the pack between pair of pressure-applying members which are an integral part of the pack. The only other (external) structure required in order to produce color prints is an exposure system including, for example, a lens, shutter, view finder, etc. in conjunction with which the pack is adapted to be employed. Each film unit comprises an integral unit which remains intact prior to, during, and subsequent to exposure and processing so that the only manipulative step is film unit withdrawal which is effective to discharge the processing liquid contents of a container within the film unit and distribute the processing liquid therewithin so as to effect dye transfer image formation while the film unit is outside of the pack, and of the camera if the pack is enclosed therein.

Since certain changes may be made in the above product without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A photographic film assemblage adapted to produce a plurality of diffusion transfer color prints comprising, in combination:

a container insertable in and removable from a photographic exposure apparatus for enclosing a plurality of film units arranged in stacked relation and including a forward wall having a light-transmitting section to permit exposure of the forwardmost filmunit, and a withdrawal opening permitting withdrawal of said forwardmost film unit following exposure thereof within said container;

a plurality of diffusion transfer process color film units each including leading and trailing ends and comprising;

a. a photosensitive laminate containing as essential layers and in order, a dimensionally stable transparent support layer, a layer adapted to receive a diffusion transfer process dye image-forming material diffusing thereto, an opaque layer, and a photosensitive silver halide layer having associated therewith a diffusion transfer process dye image-forming material;

b. a transparent dimensionally stable sheet secured in superposition and substantially coextensive with the surface of the photosensitive laminate opposite said transparent support layer; and

c. a rupturable container of a liquid processing composition including an opacifying agent positioned at said leading end of said film unit and adapted in response to the appli-cation of compressive pressure to the container to discharge its contents intermediate said dimensionally stable sheet and said photosen-sitive laminate;

said film units being arranged in stacked relation within said container with the trans-parent dimensionally stable sheets facing said forward wall and aligned with said light-transmitting section and said rupturable con-tainers located adjacent said withdrawal opening;

a pair of juxtaposed pressure-applying members associated with said withdrawal opening providing a convergent passage through which said film units are withdrawn; and

leader manually engageable for selectively withdrawing each of said film units in succession from said container between said pressure-applying members.

2. A photographic film assemblage as defined in claim 1 wherein said opaque layer of said each film unit is adapted to reflect electromagnetic radiation incident thereon.

3. A photographic film assemblage as defined in claim 2 wherein said opaque reflecting layer comprises titanium dioxide.

4. A photographic film assemblage as defined in claim 3 wherein said opacifying agent included in said processing composition comprises carbon black.

5. A photographic film assemblage as defined in claim 1 wherein said photosensitive laminate of said each film unit contains at least two selectively sensitized silver halide layers each having associated therewith a dye image-forming material adapted to provide a dye image of predetermined color as a function of the photoexposure of its associated silver halide layer.

6. A photographic film assemblage as defined in claim 5 wherein each of said selectively sensitized silver halide layers of said each film unit possesses predominant spectral sensitivity to separate regions of the spectrum and said dye image-forming material associated with each of said silver halide layers is adapted to provide a dye transfer image possessing a spectral absorption range subsequent to processing substantially complementary to the predominant sensitivity range of its associated silver halide layer.

7. A photographic film assemblage as defined in claim 6 wherein said processing composition comprises an aqueous alkaline processing composition and said color film units each include means for converting the pH of said processing composition, subsequent to substantial diffusion of said dye image-forming material to said receiving layer, from the initial pH to a second'pH at which the dye transfer image provided by said dye image-forming materials exhibits increased stability.

8. A photographic film assemblage as defined in claim 7 wherein said photosensitive laminate includes, as essential layers, a red-sensitive silver halide emulsion layer having associated therewith a diffusion transfer process cyan dye image-forming material, a greensensitive silver halide emulsion layer having associated therewith a diffusion transfer process magenta dye' image-forming material and a blue-sensitive silver halide emulsion layer having associated therewith a diffusion transfer process yellow dye image-forming material.

9. A photographic film assemblage as defined in claim 8 wherein said opaque layer comprises a first alkaline processing composition permeable polymeric layer containing titanium dioxide, said each film unit further including, contiguous the surface of said titanium dioxide containing layer intermediate that layer and the surface of said laminate opposite said transparent support layer, a second alkaline processing composition permeable polymeric layer 1 containing carbon black. I

10. A photographic film assemblage as defined in claim 1 wherein said dimensionally stable sheet of said each film unit is laminated to said photosensitive laminate.

11. A photographic film assemblage as defined in claim 10 wherein said each film unit includes binding tape securing said laminate and said dimensionally stable sheet to one another along three margins thereof and securing said container of liquid to said laminate and dimensionally stable sheet.

12. A photographic film assemblage as defined in claim 11 including a reservoir within said each film unit for collecting and retaining excess processing liquid 27 overrun beyond the trailing edge of color prints formed within said each film unit during processing thereof by said liquid.

13. A photographic film assemblage as defined in claim 1 further including a spring for urging said film unit forwardly to support the forwardmost film unit against said forward wall in position for exposure and said convergent passage is aligned with the leading end of the forwardmost film unit.

14. A photographic film assemblage as defined in claim 1 further including a restraining member permitting withdrawal of the forwardmost film unit following exposure thereof and engaging and restraining the next succeeding film unit against movement through said passage in response to frictional engagement with the forwardmost film unit.

15. A photographic film assemblage as defined in claim 14 wherein said restraining member comprises a resilient projection extending from an edge of the withdrawal opening forwardly across said opening into the path of movement of said forwardmost film unit and adapted to be deflected thereby to permit movement thereof.

16. A photographic film assemblage as defined in claim 1 wherein said juxtaposed pressure-applying members are formed of resilient sheet material shaped to form relatively rigid pressure-applying members re sistent to bending and supporting said members for limited movement apart from one another.

17. A photographic film assemblage as defined in claim 1 wherein a leader sheet is attached to each of said film units near the leading end thereof and is adapted to be moved through said passage by and in response to movement of another component of said film assemblage through said passage to provide a section of said leader sheet engageable exterior of said passage foi withdrawing said each film unit therethrough.

18. A photographic film assemblage as defined in claim 17 further including a cover element formed of an actinic light-opaque sheet material located between the forwardmost film unit and said forward wall for preventing admission of light through said light transmitting section to said film units and a leader attached to said cover element extending from said assemblage through said passage and engageable exterior of said film assemblage for withdrawing said cover element through said passage.

19. A photographic film assemblage as defined in claim 18 wherein the leader sheet of the forwardmost film unit is detachably coupled with said cover element for withdrawing said leader sheet through said passage by and in response to withdrawal of said cover element.

20. A photographic film assemblage adapted to produce a plurality of diffusion transfer color prints comprising, in combination:

a container insertable in and removable from a photographic exposure apparatus for enclosing a plurality of film units arranged in stacked relation and including a forward wall having a light-transmitting section to permit exposure of the forwardmost film unit, and a withdrawal opening permitting withdrawal of said forwardmost film unit following exposure thereof within said container;

a plurality of diffusion transfer process color film units each including leading and trailing ends and comprising:

a. a photosensitive laminate containing as essential layers and in order, a dimensionally stable transparent support layer, a layer adapted to receive a diffusion transfer process dye image-forming material diffusing thereto, an opaque layer, and a photosensitive silver halide layer having associated therewith a diffusion transfer process dye image-forming material; I

b. a transparent dimensionally stable sheet secured in superposition and substantially coextensive with the surface of the photosensitive laminate opposite said transparent support layer; and

c. a rupturable container of a liquid processing composition including an opacifying agent positioned at said leading end of said film unit and adapted in response to the application of compressive pressure to the container to discharge its contents intermediate said dimensionally stable sheet and said photosensitive laminate;

said film units being arranged in stacked relation within said container with the trans-parent dimensionally stable sheets facing said forward wall and aligned with said light-transmitting section and said rupturable containers located adjacent said withdrawal opening; and

a pair of juxtaposed pressure-applying members associated with said withdrawal opening providing a passage through which said film units are withdrawn and adapted to apply compressive force to said rupturable container to effect unidirectional discharge of the containers contents intermediate said dimensionally stable sheet and said photosenthrough said passage. 

2. A photographic film assemblage as defined in claim 1 wherein said opaque layer of said each film unit is adapted to reflect electromagnetic radiation incident thereon.
 3. A photographic film assemblage as defined in claim 2 wherein said opaque reflecting layer comprises titanium dioxide.
 4. A photographic film assemblage as defined in claim 3 wherein said opacifying agent included in said processing composition comprises carbon black.
 5. A photographic film assemblage as defined in claim 1 wherein said photosensitive laminate of said each film unit contains at least two selectively sensitized silver halide layers each having associated therewith a dye image-forming material adapted to provide a dye image of predetermined color as a function of the photoexposure of its associated silver halide layer.
 6. A photographic film assemblage as defined in claim 5 wherein each of said selectively sensitized silver halide layers of said each film unit possesses predominant spectral sensitivity to separate regions of the spectrum and said dye image-forming material associated with each of said silver halide layers is adapted to provide a dye transfer image possessing a spectral absorption range subsequent to processing substantially complementary to the predominant sensitiviTy range of its associated silver halide layer.
 7. A photographic film assemblage as defined in claim 6 wherein said processing composition comprises an aqueous alkaline processing composition and said color film units each include means for converting the pH of said processing composition, subsequent to substantial diffusion of said dye image-forming material to said receiving layer, from the initial pH to a second pH at which the dye transfer image provided by said dye image-forming materials exhibits increased stability.
 8. A photographic film assemblage as defined in claim 7 wherein said photosensitive laminate includes, as essential layers, a red-sensitive silver halide emulsion layer having associated therewith a diffusion transfer process cyan dye image-forming material, a green-sensitive silver halide emulsion layer having associated therewith a diffusion transfer process magenta dye image-forming material and a blue-sensitive silver halide emulsion layer having associated therewith a diffusion transfer process yellow dye image-forming material.
 9. A photographic film assemblage as defined in claim 8 wherein said opaque layer comprises a first alkaline processing composition permeable polymeric layer containing titanium dioxide, said each film unit further including, contiguous the surface of said titanium dioxide containing layer intermediate that layer and the surface of said laminate opposite said transparent support layer, a second alkaline processing composition permeable polymeric layer containing carbon black.
 10. A photographic film assemblage as defined in claim 1 wherein said dimensionally stable sheet of said each film unit is laminated to said photosensitive laminate.
 11. A photographic film assemblage as defined in claim 10 wherein said each film unit includes binding tape securing said laminate and said dimensionally stable sheet to one another along three margins thereof and securing said container of liquid to said laminate and dimensionally stable sheet.
 12. A photographic film assemblage as defined in claim 11 including a reservoir within said each film unit for collecting and retaining excess processing liquid overrun beyond the trailing edge of color prints formed within said each film unit during processing thereof by said liquid.
 13. A photographic film assemblage as defined in claim 1 further including a spring for urging said film unit forwardly to support the forwardmost film unit against said forward wall in position for exposure and said convergent passage is aligned with the leading end of the forwardmost film unit.
 14. A photographic film assemblage as defined in claim 1 further including a restraining member permitting withdrawal of the forwardmost film unit following exposure thereof and engaging and restraining the next succeeding film unit against movement through said passage in response to frictional engagement with the forwardmost film unit.
 15. A photographic film assemblage as defined in claim 14 wherein said restraining member comprises a resilient projection extending from an edge of the withdrawal opening forwardly across said opening into the path of movement of said forwardmost film unit and adapted to be deflected thereby to permit movement thereof.
 16. A photographic film assemblage as defined in claim 1 wherein said juxtaposed pressure-applying members are formed of resilient sheet material shaped to form relatively rigid pressure-applying members resistent to bending and supporting said members for limited movement apart from one another.
 17. A photographic film assemblage as defined in claim 1 wherein a leader sheet is attached to each of said film units near the leading end thereof and is adapted to be moved through said passage by and in response to movement of another component of said film assemblage through said passage to provide a section of said leader sheet engageable exterior of said passage for withdrawing said each film unit therethrough.
 18. A photographic film asseMblage as defined in claim 17 further including a cover element formed of an actinic light-opaque sheet material located between the forwardmost film unit and said forward wall for preventing admission of light through said light transmitting section to said film units and a leader attached to said cover element extending from said assemblage through said passage and engageable exterior of said film assemblage for withdrawing said cover element through said passage.
 19. A photographic film assemblage as defined in claim 18 wherein the leader sheet of the forwardmost film unit is detachably coupled with said cover element for withdrawing said leader sheet through said passage by and in response to withdrawal of said cover element.
 20. A photographic film assemblage adapted to produce a plurality of diffusion transfer color prints comprising, in combination: a container insertable in and removable from a photographic exposure apparatus for enclosing a plurality of film units arranged in stacked relation and including a forward wall having a light-transmitting section to permit exposure of the forwardmost film unit, and a withdrawal opening permitting withdrawal of said forwardmost film unit following exposure thereof within said container; a plurality of diffusion transfer process color film units each including leading and trailing ends and comprising: a. a photosensitive laminate containing as essential layers and in order, a dimensionally stable transparent support layer, a layer adapted to receive a diffusion transfer process dye image-forming material diffusing thereto, an opaque layer, and a photosensitive silver halide layer having associated therewith a diffusion transfer process dye image-forming material; b. a transparent dimensionally stable sheet secured in superposition and substantially coextensive with the surface of the photosensitive laminate opposite said transparent support layer; and c. a rupturable container of a liquid processing composition including an opacifying agent positioned at said leading end of said film unit and adapted in response to the application of compressive pressure to the container to discharge its contents intermediate said dimensionally stable sheet and said photosensitive laminate; said film units being arranged in stacked relation within said container with the trans-parent dimensionally stable sheets facing said forward wall and aligned with said light-transmitting section and said rupturable containers located adjacent said withdrawal opening; and a pair of juxtaposed pressure-applying members associated with said withdrawal opening providing a passage through which said film units are withdrawn and adapted to apply compressive force to said rupturable container to effect unidirectional discharge of the container''s contents intermediate said dimensionally stable sheet and said photosensitive laminate upon transit of said film units through said passage. 